DE 34 24 806 C2 has disclosed an automated digital leveling instrument, which enables an electronic rod readout. To this end, a code pattern of black and white elements is applied onto the leveling rod, a part of which code pattern is imaged on a spatially resolving detector with the aid of the telescopic optics of the electronic leveling instrument. Here, the information from the code pattern situated in the field of view of the telescope is used to obtain the desired height measurement value by comparison with the code pattern of the leveling rod stored as a reference code pattern in the leveling instrument.
Furthermore, the patent document D3 198 12 609 C2 has disclosed a method for determining the position and rotational orientation of a surgical microscope or a surgical tool such as e.g. a scalpel or endoscope. To this end, the object to be examined is registered by a plurality of cameras distributed in space and the spatial coordinates, including the rotational orientation, of the object to be examined are established from the image information. With the aid of information about the body of the patient in respect of the position and location thereof, it is possible to register, evaluate and display the precise spatial location of the object to be examined, in particular of the surgical microscope or the surgical instruments, in respect of the operation site of the human. With the aid of this information, it is also possible to guide the surgical instruments in a fully automated manner. This method was found to be very complex and complicated since it must process a large amount of data relating to the body to be operated on and relating to the image information registered by a plurality of camera-like measurement heads in order to determine reliable information in respect of the penetration depth and the rotational orientation of a medical invasive instrument or object.
Moreover, flexible endoscopes and flexible borescopes that exhibit line markings with length specifications that specify the distance of the line markings to the distal end of the shank on the flexible shank thereof are known. With the aid of these markings, the user of the flexible endoscope can estimate the penetration depth into the body during an operation, e.g. of a human, or, in the case of a borescope, estimate the penetration depth into e.g. the sewage pipe by virtue of reading the last identifiable line marking with the distance specification in the region of the body opening or the pipe opening. This type of estimating the penetration depth is very inaccurate and not automated.